1. Field of the Invention
The present invention relates to a recording and reproducing apparatus for recording and reproducing video signals and/or other types of signals. This apparatus is especially suitable for the recording and reproducing digital signals to a strip-shaped recording medium using a helical scan-type rotating head.
2. Description of the Prior Art
When using a recording and reproducing apparatus for recording and reproducing digital signals to a magnetic tape or other strip-shaped recording medium using a helical scan-type rotating head, the head path during high speed reproduction generally differs from the head path during normal reproduction (in which the reproduction head speed equals the recording head speed), and it is therefore extremely difficult during high speed reproduction to reproduce with good image quality data that was recorded for reproduction at the normal reproduction speed.
To enable high speed reproduction using the unique characteristics of helical scan recording, data for high speed reproduction is recorded in addition to the data for normal reproduction using a recording pattern different from that used for the normal reproduction data. High speed reproduction can thus be achieved using this high speed reproduction data.
It is possible, for example, to achieve high speed reproduction or very-high speed reproduction over a wide range of reproduction speeds by separately recording to the tape high speed reproduction data for use through a range of relatively low reproduction speeds, and very-high speed reproduction data for use through a range of relatively high reproduction speeds.
In FIG. 11, a tape track pattern recorded by the convention recording apparatus is shown. The head scans in a direction Hs to form plural tracks on the tape 9 which is being traveled in direction Dr. A very-high speed reproduction data are recorded in area Av; high speed reproduction data is recorded in area Ah; and normal reproduction data is recorded in area An. Since the high speed reproduction data is recorded to a area crossing each track in a continuous band, and it is therefore not possible to extend a very high speed reproduction data area Av to a maximum beyond the high speed reproduction data area Ah.
With this method, however, it is considered not possible to record the data without degrading the reproduction characteristics (bit rate during reproduction and reproduction speed range) of both the high speed reproduction data and the very-high speed reproduction data.
With a conventional recording and reproducing apparatus thus described, the high speed reproduction data used at relatively low reproduction speeds is recorded to cross bands at a predetermined position in every track, and the area available for very-high speed reproduction data is necessarily reduced by the width of these cross bands. This reduces the speed range for very-high speed reproduction. In addition, the width of the bands to which the high speed reproduction data is recorded cannot increased to reduce the effect on the very-high speed reproduction data. The track location and number of bands used for the high speed reproduction data are also limited to one band near the end of each track. As a result, the amount of data reproduced during high speed reproduction is limited, and the bit rate during reproduction is low.
The data for both high speed reproduction and very-high speed reproduction is also recorded with the same syntax used for the normal reproduction data by the above conventional recording and reproducing apparatus. If the data reproduced during normal reproduction is recorded as an MPEG signal irrespective of the data requirements during high speed reproduction and very-high speed reproduction, the standards defined by the MPEG syntax must be maintained. As a result, the bit stream for each of the reproduction speeds recorded is recorded in the form containing the header information and all other signals defined by the MPEG syntax.
This header information comprises a large part of the data for each of the reproduction speeds. As a result, the header information reduces the amount of data allocated for the video information, this video information determines the image quality during reproduction, and the header information therefore becomes a significant factor degrading image quality during high speed reproduction and increasing the image refresh cycle.
In addition, intra-frame compression data is normally used for the high speed reproduction data. With an MPEG signal, intra-frame compression data contains an extremely large volume of data, including a large quantity of code information, e.g., end-of-block (EOB) codes identifying the end of each data block, that is otherwise unnecessary. This code information thus becomes another factor contributing to degraded image quality or an increased image refresh cycle.
As a result, the real amount of recordable video information is reduced, and image quality is therefore degraded or the image refresh cycle becomes long, because the conventional recording and reproducing apparatus records with the high speed reproduction data and very-high speed reproduction data that is not part of the actual picture data.